improbable

/ɪmˈprɑbəbəl/
adjective
  1. Not likely to happen or be true.
    • Winning the race seemed improbable, but she trained hard anyway.
    • It is improbable that it will snow in July in Florida.
    • The detective thought the suspect's alibi was highly improbable.
  2. Surprising and difficult to believe because of being unusual or unexpected.
    • They made an improbable pair: a shy librarian and a loud rock musician.
    • Her improbable success inspired many young athletes.
    • The movie tells an improbable story of a dog who learns to fly.